Next generation radar systems, which are readily integrated into their host platforms and which perform multiple missions and deliver higher levels of performance with high levels of operational flexibility, employ active phased array antennas. Active phase arrays are configured from a plurality of individual radiating elements, each having phase and amplitude states that can be electronically controlled. The radiated energy from the collection of elements combines constructively (focused) so as to form a beam. The angular position of the beam is electronically redirected by controlling the elements' phases. Controlling both the elements' phases and amplitudes alters the shape of the beam. Each individual radiator of an active phased array antenna includes an initial low noise amplifier for receive mode and a final power amplifier for transmit mode, in addition to the phase and amplitude control circuitry. These active components and their support circuitry, associated with one or more array elements, are assembled into transmit/receive (T/R) units.
Most host platform limitations, especially mobile platforms, require that the radar system be assembled with components and structures having a light weight and a small volume, which operate in a reliable manner, and which are easy to maintain and/or replace. In addition, the inclusion of active components requires an effective thermal management system, preferably using air to minimize cooling system power consumption and to maximize reliability.
Conventionally, the components and circuits within the T/R units are disposed in a single plane extending rearward from the radiating element surface of the array. Consequently, the T/R units tend to be voluminous. Heat removal from the active components is initially transported by conduction within the T/R unit housing. Conventionally, the housing has a substantial metallic content so as to conduct the heat away from the components to a remote area for final heat removal. This metallic content typically leads to the T/R unit being heavy. Many active arrays employ liquid as the cooling media. The liquid is either introduced into the T/R unit or confined to an array structure that must be in close intimate contact with the T/R unit to allow effective cold plate conductive heat transfer. Due to the size, weight, and cooling techniques characteristic of conventional T/R unit designs, the integration of phased arrays incorporating such units into their platforms is problematic.